Before starting the recipe make sure that all the ingredients are at room temperature, not cold or the butter would form lumps in the batter. See recipe notes to troubleshoot butter lumps in baking.
Preheat oven to 160°C (325°F).
Grease two 9-inch round cake pans with coconut oil or butter. Cut out a piece of parchment paper into a 9-inch circle and stick it to the bottom of the pan. Grease the paper and pan sides again. These steps prevent cake from sticking to pan. Set aside.
In a large mixing bowl, add soft cubes of butter with sugar-free crystal sweetener (erythritol or allulose) and vanilla extract
Beat on low speed with an electric beater until creamy, then add the eggs, one at a time, with 15 seconds time between each addition.
Set aside the egg/butter batter.
In another bowl, combine light olive oil, apple cider vinegar, unsweetened cocoa powder and red food coloring with a spatula. Don't use coconut oil as it tends to form a paste when in contact with cocoa powder or you want the mixture to be liquid for the best cake texture.
Using a baking spatula, stir in the previous cocoa mixture into the first bowl with the egg/butter mixture.
Add in the almond flour, baking powder and unsweetened almond milk.
Beat on low speed to combine and form a smooth cake batter, with no lumps.
Cake decoration - optional
Scoop out 1/4 cup of cake batter and spread in a thin layer, on a separate baking tray, covered with a piece of oiled baking paper. Bake this cake layer at 160°C (325°F) for 10 minutes or until set. crumble this to decorate the top of the cake!
Cool down then crumble with your fingers to form a red crumb and decorate the cake at the end.
Bake the cake layers
Fill each greased baking pan evenly, usually each layer will be made of about 2 cups of cake batter. Spread the batter evenly with a spatula, then tap the baking pan few times on the bench-top to make sure you removed any air bubbles locked in the batter.
Bake for 22-30 minutes in the center of your oven, fan-bake mode is ideal if you have one otherwise use regular mode (same temperature). Your cake is cooked when the top is still soft, moist and a skewer inserted in the middle of the cake come out clean, with no crumbs stick on the skewer. Note: this is a gluten-free cake, it won't raise and form 2 moist, thin, flat cake layers of red velvet cake layer.
Remove from the oven, cool 5 minutes in the pan then unmold and cool on a cooling rack until it reaches room temperature - about 1 hour.
In a large mixing bowl, beat soft cream cheese with soft butter, powdered erythritol and vanilla.
Place the first layer of cake onto a cake frosting turning table, then add 1/3 of the frosting in the the center of the cake layer. Spread with a spatula, turning the cake frosting table at the same time to spread evenly.
Place the second cake layer on top of the previous on, add more frosting and repeat the previous step to cover the top and side of the cake.
Cut the cake in 12 slices and serve one slice as one serve.
Store leftover frosting in an airtight container in the fridge and eat as a zero-carb keto snack. You can also freeze this frosting in ice cube tray to make single-serve keto frozen snack treats.
Store the cake in an airtight cake box in the fridge for up to 3 days or freeze in slices in airtight container. Defrost the day before at room temperature.
How to troubleshoot butter lumps in cake batter? This happens if you are using cold butter or cold eggs. To fix the issue, prepare a large baking bowl with hot water. Place the baking bowl (with the butter/erythritol mixture) on top of the hot bowl (this is called 'bain-marie'). The heat from the warm bowl will transfer to the cake batter bowl gently, as you keep stirring the butter/erythritol mixture the lumps will disappear.